The westbound tunnel was badly damaged by a fire when a truck exploded inside it in 2011.
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It is understood that the works contract will include upgrading the lighting, after the tunnel was fitted with temporary lights following the fire.
Improvements to the Malpas Viaduct and Usk River Bridge are also included in the contract package which will be let as an early contractor involvement deal.
Contractors have until 19 December to submit their interest. The work is scheduled to begin next year.
(MH/JP)
